Finite element formulation of different restoring stiffness issues in the ship hydroelastic analysis and their influence on response

Two different restoring stiffness formulations for ship hydroelastic analysis are considered, i.e., a consistent one, as an extension of the ordinary restoring stiffness in ship rigid body motion in waves, and another structurally oriented one, which comprises geometric stiffness with ship stress distribution in calm seas. In order to increase the accuracy of the stiffness coefficients in modal analyses the finite element technique is employed. Triangular and rectangular finite elements are worked out for panels of wetted surface and structural members, i.e., plates and beams. The geometric stiffness matrix consists of three parts, one related to plate deflection, well-known in the buckling analysis, and two additional for membrane displacements, which complete expression for ship stability. For all three parts the same shape functions of membrane displacement are used for reasons of simplicity. A special software for generation of restoring stiffness is developed and incorporated in the package for ship hydroelastic analysis. The hydroelastic response of a thin-walled barge is determined by employing the consistent restoring stiffness in two variants, i.e., with a distributed structural mass and lumped masses, and the complete restoring stiffness. The response includes the transfer functions of rigid body and elastic modes, and those for vertical, horizontal and torsional sectional forces. Moderate differences of three sets of calculations are noticed in a narrow region of the lower frequency range. Some valuable conclusions based on that numerical test are drawn.


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  • Accession Number: 01487153
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jun 4 2013 12:35PM